Alinity c instrument

AKI was defined using the Kidney Disease: Improving Global Outcomes (KDIGO) criteria based on a 1.5-fold increase in serum creatinine from estimated baseline and staged as follows: stage 1, 1.5–1.9-fold increase in creatinine over baseline; stage 2, 2.0–2.9-fold increase over baseline; stage 3 ≥ 3.0-fold increase over baseline. Baseline creatinine was estimated using a height-independent approach, assuming a GFR of 120 mL/min per 1.73 m² as described [49 (link)]. AKI was classified as severe if it was stage 2 or 3 [50 (link)]. Creatinine was tested using the modified Jaffe colorimetric method on an Alinity c instrument (Abbott, Lake Forest, IL, USA), which is traceable to an isotope dilution mass spectrometry (IDMS) reference method. Cystatin C was included as an alternative functional marker of AKI measured by Luminex (R&D Systems, Minneapolis, MN, USA) and classified as positive if levels were > 0.8 mg/L [31 (link)].

The levels of the enzymes alanine aminotransferase (ALT, in μkat/L), alkaline phosphatase (ALP, in μkat/L), aspartate aminotransferase (AST, in μkat/L), γ-glutamyl transferase (GGT, in μkat/L) and total bilirubin (TBIL, in μmol/L) in blood serum were considered as markers of liver function. Total serum cholesterol (CHOL, mmol/L) and low-density lipoprotein (LDL, mmol/L) were considered as indicators of blood serum lipids. Both liver and lipid biomarkers were measured spectrophotometrically with an Alinity c instrument (©Abbott, Illinois, USA).
8-hydroxy-2’-deoxyguanosine (8OHdG), a biomarker of oxidative stress, was measured in urine by LC–MS/MS following the method described in detail previously (Bláhová et al. 2023 (link)). Briefly, thawed urine samples (500 µL) were spiked with internal standard (15N5-8-hydroxy-2′-deoxyguanosine), vortexed, and then lyophilized. After extraction with isopropanol, supernatants were evaporated to dryness and redissolved in 0.1% formic acid (v/v), and the final extracts were stored at -20 °C until LC–MS/MS analysis.